To reduce the number of bus lines need to communicate and power a bus interface system, it would be desirable for slave bus controllers to derive power from an input data signal so that a separate bus line does not have to be provided in order to power the slave bus controller. This is highly advantageous in modern cellular telephones in which space is at a premium and running multiple bus lines between a master bus controller device and slave bus controller can be spatially inefficient.
The problem is that any power system that receives power from the input data signal needs to maintain storage elements isolated from the bus line but then needs to use power in those storage elements to send data along the same bus line. Unfortunately, in current power systems the supply voltage of the slave bus controller slowly droops and cannot maintain the appropriate charge. Thus, what are need are systems that derive power from the input data signal while maintaining the appropriate charge